Conventionally, a technology has been proposed for controlling air-intake into an engine by providing an intake control valve in an air-intake path upstream from an intake valve; one example thereof is disclosed in Japanese Patent Application Laid-open No. 2000-248946. The intake control valve disclosed therein continuously remains at an open position so that the air-intake path is open as far as the super-charging is not desired. On the other hand, when the super-charging is desired, the intake control valve is operated to occupy a closed position at an initial stage of the intake stroke during the operation of the engine so that the air-intake path is closed, and then suddenly operated in the opening direction when the pressure difference becomes large between the upstream and the downstream from the intake control valve in the air-intake path, to open the air-intake path. Thus, air in the air-intake path is strongly accelerated by the negative pressure downstream from the intake control valve so that the charging efficiency thereof is facilitated. The supercharging obtained in such a manner is referred to as a so-called “impulse supercharging”.
In this regard, the summary of the above-mentioned impulse supercharging is also described in the paper published on September 9, in Frankfurt Motor Show 2003, titled as “Impulses for Greater Driving Fun” by Siemens VDO Automotive AG.